CVE-2021-41773

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 5 sources updated this weekExploited in the wild
9.8EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 100%CVSS: 9.8Exploit: cisa kev · ssvc active · kev ransomware · Metasploit · Exploit-DB (verified) · epss top5pct · epss high · public exploitExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default configuration "require all denied", these requests can succeed. If CGI scripts are also enabled for these aliased pathes, this could allow for remote code execution. This issue is known to be exploited in the wild. This issue only affects Apache 2.4.49 and not earlier versions. The fix in Apache HTTP Server 2.4.50 was found to be incomplete, see CVE-2021-42013.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
99(Act)
EG Risk 99/100SSVC: Act

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation100% × 40%
Automatability100% × 15%
Action: Fix now — active exploitation, automatable, high impact.
EPSS PROB
100%
EPSS %ILE
100%
KEV
⚠ Exploited

Published

October 5, 2021

Last Modified

February 17, 2026

Advisory Details (6)

Auto-updated Jul 27, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic

oss-security - Re: CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

http://www.openwall.com/lists/oss-security/2021/10/08/3
generic

oss-security - Re: CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

http://www.openwall.com/lists/oss-security/2021/10/08/2
generic

oss-security - Re: CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

http://www.openwall.com/lists/oss-security/2021/10/08/1
generic

oss-security - CVE-2021-42013: Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)

http://www.openwall.com/lists/oss-security/2021/10/07/6
generic🔴 Active Exploitation

oss-security - RE: CVE-2021-41773: Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

http://www.openwall.com/lists/oss-security/2021/10/07/1
generic🔴 Active Exploitation

oss-security - CVE-2021-41773: Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

http://www.openwall.com/lists/oss-security/2021/10/05/2

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 58× in last 7d / 359× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 752 total refreshes for this CVE.

  1. 2026-07-29 22:49 UTCVendor advisory
  2. 2026-07-29 22:49 UTCGHSA enrichment
  3. 2026-07-29 19:27 UTCCISA KEV update
  4. 2026-07-29 19:06 UTCVendor advisory
  5. 2026-07-29 19:06 UTCGHSA enrichment
  6. 2026-07-29 15:25 UTCVendor advisory
  7. 2026-07-29 15:25 UTCGHSA enrichment
  8. 2026-07-29 11:44 UTCVendor advisory
  9. 2026-07-29 11:44 UTCGHSA enrichment
  10. 2026-07-29 08:02 UTCVendor advisory
  11. 2026-07-29 08:02 UTCGHSA enrichment
  12. 2026-07-29 04:21 UTCVendor advisory
  13. 2026-07-29 04:21 UTCGHSA enrichment
  14. 2026-07-29 00:40 UTCVendor advisory
  15. 2026-07-29 00:39 UTCGHSA enrichment
  16. 2026-07-28 20:58 UTCVendor advisory
  17. 2026-07-28 20:58 UTCGHSA enrichment
  18. 2026-07-28 17:14 UTCVendor advisory
  19. 2026-07-28 17:14 UTCGHSA enrichment
  20. 2026-07-28 13:31 UTCVendor advisory
  21. 2026-07-28 13:31 UTCGHSA enrichment
  22. 2026-07-28 09:48 UTCVendor advisory
  23. 2026-07-28 09:47 UTCGHSA enrichment
  24. 2026-07-28 06:06 UTCVendor advisory
  25. 2026-07-28 06:06 UTCGHSA enrichment
Show 75 more
  1. 2026-07-28 02:23 UTCVendor advisory
  2. 2026-07-28 02:23 UTCGHSA enrichment
  3. 2026-07-27 22:42 UTCVendor advisory
  4. 2026-07-27 22:42 UTCGHSA enrichment
  5. 2026-07-27 19:24 UTCCISA KEV update
  6. 2026-07-27 18:58 UTCVendor advisory
  7. 2026-07-27 18:58 UTCGHSA enrichment
  8. 2026-07-27 17:17 UTCCISA KEV update
  9. 2026-07-27 15:07 UTCVendor advisory
  10. 2026-07-27 15:06 UTCGHSA enrichment
  11. 2026-07-27 11:24 UTCGHSA enrichment
  12. 2026-07-27 07:43 UTCVendor advisory
  13. 2026-07-27 07:42 UTCGHSA enrichment
  14. 2026-07-27 04:01 UTCVendor advisory
  15. 2026-07-27 04:00 UTCGHSA enrichment
  16. 2026-07-27 00:19 UTCVendor advisory
  17. 2026-07-27 00:18 UTCGHSA enrichment
  18. 2026-07-26 20:35 UTCVendor advisory
  19. 2026-07-26 20:35 UTCGHSA enrichment
  20. 2026-07-26 16:53 UTCVendor advisory
  21. 2026-07-26 16:53 UTCGHSA enrichment
  22. 2026-07-26 13:11 UTCEG score recompute
  23. 2026-07-26 13:11 UTCVendor advisory
  24. 2026-07-26 13:11 UTCGHSA enrichment
  25. 2026-07-26 09:30 UTCVendor advisory
  26. 2026-07-26 09:30 UTCGHSA enrichment
  27. 2026-07-26 05:48 UTCVendor advisory
  28. 2026-07-26 05:48 UTCGHSA enrichment
  29. 2026-07-26 02:04 UTCEG score recompute
  30. 2026-07-26 02:04 UTCVendor advisory
  31. 2026-07-26 02:03 UTCGHSA enrichment
  32. 2026-07-24 14:15 UTCEPSS rescore
  33. 2026-07-23 02:04 UTCEG score recompute
  34. 2026-07-22 22:29 UTCEG score recompute
  35. 2026-07-22 22:29 UTCVendor advisory
  36. 2026-07-22 22:29 UTCGHSA enrichment
  37. 2026-07-22 19:40 UTCCISA KEV update
  38. 2026-07-22 18:46 UTCGHSA enrichment
  39. 2026-07-22 15:04 UTCVendor advisory
  40. 2026-07-22 15:04 UTCGHSA enrichment
  41. 2026-07-22 11:22 UTCVendor advisory
  42. 2026-07-22 11:22 UTCGHSA enrichment
  43. 2026-07-22 07:40 UTCVendor advisory
  44. 2026-07-22 07:40 UTCGHSA enrichment
  45. 2026-07-22 03:59 UTCVendor advisory
  46. 2026-07-22 03:59 UTCGHSA enrichment
  47. 2026-07-22 00:13 UTCVendor advisory
  48. 2026-07-22 00:13 UTCGHSA enrichment
  49. 2026-07-21 20:31 UTCVendor advisory
  50. 2026-07-21 20:31 UTCGHSA enrichment
  51. 2026-07-21 16:47 UTCVendor advisory
  52. 2026-07-21 16:47 UTCGHSA enrichment
  53. 2026-07-21 14:37 UTCCISA KEV update
  54. 2026-07-21 13:05 UTCVendor advisory
  55. 2026-07-21 13:05 UTCGHSA enrichment
  56. 2026-07-21 09:23 UTCVendor advisory
  57. 2026-07-21 09:23 UTCGHSA enrichment
  58. 2026-07-21 05:41 UTCVendor advisory
  59. 2026-07-21 05:41 UTCGHSA enrichment
  60. 2026-07-21 01:58 UTCVendor advisory
  61. 2026-07-21 01:58 UTCGHSA enrichment
  62. 2026-07-20 22:17 UTCVendor advisory
  63. 2026-07-20 22:16 UTCGHSA enrichment
  64. 2026-07-20 18:34 UTCVendor advisory
  65. 2026-07-20 18:34 UTCGHSA enrichment
  66. 2026-07-20 14:53 UTCGHSA enrichment
  67. 2026-07-20 11:12 UTCGHSA enrichment
  68. 2026-07-20 07:30 UTCVendor advisory
  69. 2026-07-20 07:30 UTCGHSA enrichment
  70. 2026-07-20 03:49 UTCVendor advisory
  71. 2026-07-20 03:49 UTCGHSA enrichment
  72. 2026-07-20 00:07 UTCVendor advisory
  73. 2026-07-20 00:07 UTCGHSA enrichment
  74. 2026-07-19 20:26 UTCVendor advisory
  75. 2026-07-19 20:26 UTCGHSA enrichment

Publicly available exploits

(10 references)

Working exploit code is in the public domain (8 GitHub PoCs) (2 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-50512✓ verified
    First seen Nov 11, 2021

    Apache HTTP Server 2.4.50 - Remote Code Execution (RCE) (3)

    Open source ↗
  • GitHub PoCMrCl0wnLab/SimplesApachePathTraversal
    First seen Oct 13, 2021

    Tool check: CVE-2021-41773, CVE-2021-42013, CVE-2020-17519

    Open source ↗
  • GitHub PoCinbug-team/CVE-2021-41773_CVE-2021-42013
    First seen Oct 9, 2021

    CVE-2021-41773 CVE-2021-42013漏洞批量检测工具

    Open source ↗
  • GitHub PoCim-hanzou/apachrot
    First seen Oct 9, 2021

    Apache (Linux) CVE-2021-41773/2021-42013 Mass Vulnerability Checker

    Open source ↗
  • GitHub PoCHightechSec/scarce-apache2
    First seen Oct 7, 2021

    A framework for bug hunting or pentesting targeting websites that have CVE-2021-41773 Vulnerability in public

    Open source ↗
  • GitHub PoCjustakazh/mass_cve-2021-41773
    First seen Oct 7, 2021

    MASS CVE-2021-41773

    Open source ↗
  • Exploit-DBEDB-50383✓ verified
    First seen Oct 6, 2021

    Apache HTTP Server 2.4.49 - Path Traversal & Remote Code Execution (RCE)

    Open source ↗
  • GitHub PoCblasty/CVE-2021-41773
    First seen Oct 6, 2021

    CVE-2021-41773 playground

    Open source ↗
  • GitHub PoCBlueTeamSteve/CVE-2021-41773
    First seen Oct 6, 2021

    Vulnerable docker images for CVE-2021-41773

    Open source ↗
  • GitHub PoCiilegacyyii/PoC-CVE-2021-41773
    First seen Oct 5, 2021
    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2021-41773?
CVE-2021-41773 is a critical vulnerability published on October 5, 2021. A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default…
When was CVE-2021-41773 disclosed?
CVE-2021-41773 was first published in the National Vulnerability Database on October 5, 2021, with the most recent update on February 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-41773 actively exploited?
Yes. CISA added CVE-2021-41773 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Apache HTTP Server. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-41773?
CVE-2021-41773 has a CVSS v3 base score of 9.8 (NVD).
Which products are affected by CVE-2021-41773?
CVE-2021-41773 affects Apache HTTP Server. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2021-41773?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-41773, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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